Daytek F19AH

[UserName666]

Re: Daytek F19AH

I shall hunt down a 10uf 50v cap. Thanks for the quick reply.

[retiredcaps]

Re: Daytek F19AH

The only two I did not change were the 10uf 50v or the big filter cap beside it as I didn't have those.

I find the noise to be coming from the yellow transformer beside the large filter cap.

I believe the 10uF 50V cap is the startup/run cap. These little caps do not have to bloat in order to be bad. It could have high ESR (ohm) or have incorrect uF.

The SMPS is clicking as it tries to startup.

I suggest replacing that little cap and retesting.

[UserName666]

Re: Daytek F19AH

Wondering if anything ever came of this thread/monitor? I have the same monitor but it is a F19DH...SAME POWER BOARD though. It will not power up at all. No power light or anything. Opened it and there was one bulged 470uf 25v cap. I replaced that along with the other 470uf as well as both 220uf and the 100uf but they are all 50v now. The only two I did not change were the 10uf 50v or the big filter cap beside it as I didn't have those. Still no power light or anything. Before I replaced the caps I noticed there was a steady clicking noise coming from the board when plugged in and the clicking still remains after replacing all the caps. Using one of those stethascope things for finding engine noise (it works) and I find the noise to be coming from the yellow transformer beside the large filter cap. Is that transformer supposed to make a steady but very quiet clicking noise or is that the next thing to replace? (In the first picture the big black cap behind the blue 470uf is the original one that was bulged and the first one I tried replacing. It was identical to the blue 470 thats in the pic. There were two of them.)

[davg]

Re: Daytek F19AH

I should pay better attention (I think I hear PB sighing somewhere); the power and inverter boards are combined.

What are the markings on IC101 (rear side, upper center), and Q13 and Q14 (rear side, center)? Find the data sheet on IC101 and make sure the output voltage is within range, and check Q13/Q14 for shorts. Also, what are the markings on IC1 and IC4 (rear side, right)?

Thanks Wrog the markings are very difficult to read on IC101 looks like 568415z? the 5 could be an S bottom # looks like KZA037605190?
IC1 markings look like 129932GN top 0505A center and 13096601T bottom and on IC4 393 top E450 bottom. I have no idea where to find data sheets for these componets? I have not tested the Q13/Q14 yet still have to do some reading on testing transistors in circuit.

[Wrog]

Re: Daytek F19AH

Thanks Wrog for your post. When connected to the computer the light stays green. I didn't replace the small cap next to the big one because I didn't have a suitable replacement. Not sure where to measure the voltage to the inverter. I will post a picture of the logic board in the morning.

I should pay better attention (I think I hear PB sighing somewhere); the power and inverter boards are combined.

What are the markings on IC101 (rear side, upper center), and Q13 and Q14 (rear side, center)? Find the data sheet on IC101 and make sure the output voltage is within range, and check Q13/Q14 for shorts. Also, what are the markings on IC1 and IC4 (rear side, right)?

[davg]

Re: Daytek F19AH

Thanks Wrog for your post. When connected to the computer the light stays green. I didn't replace the small cap next to the big one because I didn't have a suitable replacement. Not sure where to measure the voltage to the inverter. I will post a picture of the logic board in the morning.

[Wrog]

Re: Daytek F19AH

What does it do when it's hooked up to a known good video source (might be good to check all available input types - D-sub, component, DVI, HDMI, etc.)?

Changed all caps except one a 10uf@50v.

I'm curious to know the reason this cap was left alone? If it's the short guy next to the filter cap (the big fat guy laying down) then it's a part of the startup circuit and provides critical voltages to the controller IC.

The voltages to the logic card sound fine; have you measured the voltage to the inverter? Pictures of the logic card and inverter may yield more clues.

[davg]

Daytek F19AH this unite powers on with green light and fades to orange when not connected to computer. The back lights will not light. Changed all caps except one a 10uf@50v.. Checked the voltages as follows; across large capacitor 169v. from gr to red to the logic board 11.98v across Q13 and 14 11.98 v 9.6 v dc on T1 from center to either leg. The resistance on T101 black to white wire in infinite. Not sure what these readings meen if any thing? From what I can read this would indicate that the ac and dc is working?? Any suggestions